Question

Write an equation of the line through (-4,0) and (6,-1). Write the equation in standard form.

Answer 1

standard form for a linear equation means

• all coefficients must be integers, no fractions

• only the constant on the right-hand-side

• all variables on the left-hand-side, sorted

• "x" must not have a negative coefficient

`(\stackrel{x_1}{-4}~,~\stackrel{y_1}{0})\qquad (\stackrel{x_2}{6}~,~\stackrel{y_2}{-1}) \\\\\\ \stackrel{slope}{m}\implies \cfrac{\stackrel{rise} {\stackrel{y_2}{-1}-\stackrel{y1}{0}}}{\underset{run} {\underset{x_2}{6}-\underset{x_1}{(-4)}}} \implies \cfrac{-1 -0}{6 +4} \implies \cfrac{ -1 }{ 10 } \implies - \cfrac{1 }{ 10}`

`\begin{array} \cline{1-1} \textit{point-slope form}\\ \cline{1-1} \\ y-y_1=m(x-x_1) \\\\ \cline{1-1} \end{array}\implies y-\stackrel{y_1}{0}=\stackrel{m}{- \cfrac{1 }{ 10}}(x-\stackrel{x_1}{(-4)}) \implies y -0 = - \cfrac{1 }{ 10} ( x +4) \\\\\\ y=- \cfrac{1 }{ 10}(x+4)\implies \stackrel{\textit{multiplying both sides by }\stackrel{LCD}{10}}{10(y)=10\left( - \cfrac{1 }{ 10} ( x +4) \right)}\implies 10y=-(x+4) \\\\\\ 10y=-x-4\implies {\Large \begin{array}{llll} x+10y=-4 \end{array}}`